[Epidemiological and etiological surveillance study of infectious diarrhea in Shanghai in 2013-2015].

Objective

To analyze the pathogen spectrum and epidemiological characters of infectious diarrhea cases in Shanghai from July 2013 to June 2015.

Methods

From July 2013 to June 2015, using multi-stage sampling to select 22 hospitals as adult diarrhea surveillance sentinels, and 3 district central hospitals together with Shanghai municipal children's hospital as children diarrhea surveillance sentinels. A total of 6 267 diarrhea cases were sampled. The demographic characters, main clinical manifestations and signs of cases were investigated, and stool specimens were collected to conduct the bacteria culture and virus nucleic acid detection. The difference of positive rate of bacteria and virus in different seasons, and age difference of relevant pathogens were compared.

Results

Among 6 267 cases, 3 262 (52.05%) were male, and most of them were in 50-69 years group (1 999 cases, 31.90%) and 30-49 years group (1 691 cases, 26.98%). Totally, 2 783 positive specimens were detected out of 6 267 specimens with the positive rate being 44.41%. A total of 7 kinds of bacteria and 5 kinds of viruses were detected. The positive rate for bacterium was 12.61%(790 cases), mainly being vibrio parahaemolyticus (256 cases), diarrheagenic E.coli (239 cases) and salmonella (209 cases). The positive rate for virus was 31.80% (1 993 cases), mainly being norovirus (1 172 cases) and rotavirus (546 cases). The positive rates of viruses in winter of 2013 and 2014 were 57.89%(429 cases) and 62.14%(522 cases) respectively, higher than those of bacterium in the same periods which were 2.43% (18 cases) and 2.86% (24 cases) respectively. The positive rates of bacterium in summer of 2013, 2014 and 2015 were 14.56% (97 cases), 25.29%(258 cases) and 21.21% (49 cases), also higher than those of viruses in the same periods which were 7.51% (50 cases), 8.43%(86 cases) and 11.69% (27 cases) respectively, all of the above differences were statistically significant (P<0.05). The cases of 50-69 years group had the highest positive rate of pathogen, which was 47.57% (951/1 999). Secondly was those of 30-49 years group with 47.13% (797/1 691). Positive rate of pathogen for cases of 0-2 years group was 35.74% (213/596).

Conclusion

The pathogen spectrumes of infectious diarrhea in Shanghai are mainly vibrio parahaemolyticus, diarrheagenic E.coli, salmonella, norovirus and rotavirus. The summer and winter season peak was obvious. Specific etiological surveillance and control strategies should be strengthened aiming at focus groups including children and the elderly in different seasons.